1. Field of the Invention
The present invention relates generally to internal combustion engine control apparatuses and particularly to removing a deposit formed in an intake port.
2. Description of the Background Art
An internal combustion engine combusts an air fuel mixture in a cylinder to obtain power. The cylinder is provided with an intake valve and an exhaust valve. At the intake stroke when the intake valve opens, air (or an air fuel mixture) is introduced into the cylinder, and at the exhaust stroke when the exhaust valve opens, the air fuel mixture combusted (or exhaust gas) is exhausted external to the cylinder. To allow the internal combustion engine to efficiently introduce air into the cylinder, the intake valve is opened at the exhaust stroke slightly before the piston reaches the top dead center, when the exhaust gas can be blown back into an intake pipe. This causes a particulate matter present in the exhaust gas to be deposited at the intake port. This deposit must be removed.
Japanese Patent Laying-Open No. 2003-129923 discloses a fuel injection device capable of reducing and removing a deposit. As described in the publication, the fuel injection device includes a high pressure fuel pump, a controller, first injection valves, one for each cylinder of the internal combustion engine, and at least one second injection valve allowing fuel to be injected into an intake pipe.
As described in the publication, the fuel injection device allows fuel to temporarily be injected into the intake pipe through the second injection valve to contribute to a reduced deposit or remove a formed deposit.
How the fuel is sprayed in the intake port is influenced by how air flows in the intake port. The fuel injection device described in the publication, however, fails to consider how air flows in the intake port, and has a possibility of a reduced deposit removal effect.